Automatic irrigation control means



Nov. 30, 1954 J. F. HASENKAMP AUTOMATIC IRRIGATION CONTROL MEANS FiledSept. 9, 1949 FIG.

FIG. I.

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.of moisture in the soil.

United States Patent AUTOMATIC IRRIGATION CONTROL MEANS John F.Hasenkamp, North Hollywood, Calif. Application September 9, 1949, SerialNo. 114,743

Claims. (Cl. 315-76) This invention has to do generally with electricalcontrol apparatus and more particularly the automatic electrical controlof irrigation systems.

An object of the invention is to provide a novel effective means ofcontrolling the amount of water supplied to a given area of land by anirrigation system in response to the moisture requirements of the soil.

A further object of the invention is to provide an electrical meanswhich is responsive to moisture or the absence of same and which may beused to operate or control various power circuits useful for an infinitevariety of purposes.

Another object of the invention is to provide a new and improved simplemeans of determining the amount In this connection it is an object toprovide a novel moisture detector or moisture sensitive device and anovel method of using the same to give an accurate indication of thewetness of the soil.

More particularly, an object of the invention is to provide anelectrical system or means for automatically controlling a plurality ofirrigation pipes or the like in which the system as a whole may beenergized periodically at desired intervals and which, when energized,will operate to supply water to only such of the pipes as furnish waterto areas of land in need of it. In this connection, a further object isto provide such a system which is adjustable so that it may be set tooperate to supply water only when the soil has less than a predetermined or given amount of moisture.

A still further object is to provide such a system wherein the moisturedetector units may be so located in the soil and so connected as toachieve the desired depth of irrigation of the soil in a given area.

These and other objects will be apparent from the drawing and thefollowing'description.

Referring to the drawing, which is merely illustrative of certain formsmy invention may take:

Fig. l is a diagrammatic view of an irrigation system and contol meanstherefor, embodying my invention;

Fig. 2 is a schematic wiring diagram of the electrical control circuits;

Fig. 3 is a longitudinal sectional view of a detector unit buried in theground;

Fig. 3A is a section on line 3A-3A of Fig. 3;

Fig. 4 is a diagrammatic view of one means of operating the valves inthe water lines; and

Fig. 5 is a diagrammatic view of another means of operating the valvesin the water lines.

More particularly describing the invention, in Figs. 1-3 I show a simpleirrigation system embodying the invention. Referring to these figures,numeral 11 indicates a water supply pipe which it may be assumed isconnected to a source of water under pressure. Two branch irrigationpipes 12a and 12b are shown leading from pipe 11, the branch pipes beingprovided with suitable outlets as sprinkler heads 13. In an actualinstallation, the pipes would usually be laid under the surface of thesoil and the outlets or sprinkler heads disposed at desired elevationsabove the surface. Any number of branch pipes and outlets are provided,depending upon the area to be covered and the water pressure available.

Supply of water to the branch pipes is controlled by valves 15a and 1511which are normally closed. The valves are opened by solenoids 16a and16b which will be described later.

In each section of ground covered by each branch ir- 2,695,976 PatentedNov. 30, 1954 rigation pipe I provide moisture detector means and inFig. 1 I show detector units 1811 associated with branch pipe 12a anddetector units 18b associated with branch pipe 121). These units may beburied in the ground at a desired depth which will vary depending uponthe nature of the soil and the vegetation being irrigated. The units ineach section are connected electrically to a control unit, generallyindicated by 20.

The control unit, when energized, is adapted to supply currentsuccessively to the detector units in each area of soil to be irrigatedand successively to power circuits for operating the solenoids whichactuate the valves. In a typical operation, current is first supplied toa detector circuit including detector units 18:: and to a power circuitincluding solenoid 16a. If the soil in which units 18a are buried is notsufiiciently moist, continued flow of current through solenoid 16a opensvalve 15a thereby supplying water to branch pipe 12a. When the area hashad enough water, or if it was originally sufficiently moist, thedetector units pass sufiicient current to cause the control unit todeenergize the detector and power circuits including, respectively,units 18a and solenoid 16a and to energize circuits including units 1812and solenoid 16b. The cycle is then repeated for the section covered bypipe 126 and as many additional sections as may be embodied in thesystem. The means whereby this is accomplished will now be described indetail.

Referring particularly to Fig. 2 for a description of the control unit20, this unit is adapted to be connected to a suitable source ofalternating current, such as a conventional ll5-volt supply, by means ofleads 21 and 22. Wires 21a and 220 form continuations of the leads andare connected to form what will be called the A. C. supply circuitthrough the primary coil of a transformer '24. A manual switch (notshown) may be provided in this circuit if desired. Preferably I providea time or clock switch 25 in the circuit so that the system may be fullyautomatic and be set to operate at any desired time as at night, forinstance, when the water pressure in city mains is usually relativelyhigh. The time switch may be of a conventional type which closes thecircuit at periodic intervals, as once every twenty-four hours, for ashorter period of time, say one or two hours, and then opens thecircuit.

I may also provide a thermostatically controlled switch 27 in thiscircuit as a safety feature for the purpose of opening the circuit whenthe temperature is so low that there would be danger of the waterfreezing in the pipes.

The control unit includes what will be termed a moisture detectorcircuit, generally indicated by 30. This includes the secondary windingof transformer 24 and the primary winding of a transformer 31. I preferto employ a somewhat lower voltage in this circuit than in the supplycircuit and this may conveniently be 24 volts. In the original or normalposition of the device this circuit is closed through conductors 32, 33,and 33a and a normally closed relay switch 34. However, as will later beexplained, after initial energization of the controller, switch 34 opensand remains open until time switch 25 opens the A. C. supply circuit.Included in circuit 30 is a detector unit selector switch 36 havingcontacts 37a, 37b, 370, etc., the first two of which are shown connectedto the detector units 18a and 18b, respectively, by conductors 39a and39b. The movable con-- tact arm 38 of the switch is connected toconductor 33 and, when in its original position, rests on a contactbutton 40 which is connected to switch 34 by conductor 33a, therebycompleting the detector circuit as aforementioned. A common lead 41 runsfrom conductor 32 to the detector units.

A power circuit selector switch is provided for successively supplyingcurrent to the solenoids for operating the valves. This switch,indicated by numeral 42, has a movable contact arm 43 which is connectedto conductor 21a. This arm originally makes contact with a dead contactpoint 44. Other contact points 45a, 45b, 450, etc., are provided, onefor each valve-operating solenoid. The first two of these are shownconnected to the solenoids 16a and 16b by conductors 46a and 4617. Acommon lead 47 runs from conductor 22a to the several solenoids.

The two selector switches are ganged together in any manner to beadvanced one contact for each energization of a step relay 48 which isconnected across conductors 50 and 51 supplying direct current to arelay 54. A rectifier is indicated at 52. Included in the circuit withthe step relay is a normally open switch 55 forming part of a relay 56,the coil of which is in series in the plate circuit of a cold cathodetube 58. The grid of the tube is connected to transformer 31 through themedium of a potentiometer 60. The cathode is connected to the sametransformer and to negative supply conductor 56.

A step relay breaker switch 48a is connected in series in the platecircuit of the tube and this switch opens upon energization of steprelay 48 after a time delay sufiicient for the relay to advance theselector switches. A conventional step or stepping relay may be used andconnected electrically as shown and described herein.

After initial energization of the control unit, as by closing of timeswitch 25, switch 34 opens and thereafter the amount of current flowingthrough the moisture detection circuit 30 is governed by the impedanceofiered by detector unit or units in the circuit at any given timethrough which the current must flow to complete the circuit. In order tohold switch 34 closed long enough after initial energization of thecontrol unit to accomplish the first actuation of the step relay 48, acondenser 64 is connected across the relay intermediate resistors 65.Thus, when the control unit circuits are initially energized thedetector circuit is closed through switch 34 and starter voltage isfurnished the tube whereby to cause current flow in the plate circuit ofthe tube. This latter closes switch 55 of relay 56 thereby energizingstep relay 48 which actuates the selector switches for the firstoperation thereof. Relay 48 subsequently opens breaker switch 48a in theplate circuit with the result that switch 55 opens and relay 48 becomesdeenergized.

In Figs. 3 and 3A I show a preferred form of moisture detector unitadapted to be buried in the soil 70. The unit comprises an outerelectrode 71 in the form of an apertured metal casing. Within this ismounted an inner metal electrode 72. Porcelain or other insulationbushings 73 and 74 serve to mount the two electrodes in spaced relationleaving a space 75 therebetween which is filled with soil. The bushing73 encloses the end of the inner electrode at one end. The other endprojects through bushing 74, receiving an insulated conductor 76. A plug77 of an insulative and sealing material covers this end of the innerelectrode. 79 is attached to the outer electrode. It will be apparentthat the electrodes may be formed of various materials. However, Iprefer to utilize non-corrodible metals for this purpose.

As previously indicated, I prefer to employ two moisture detector unitsfor each area to be irrigated by a branch irrigation pipe. However, itis only necessary to employ one such unit and more than two may be usedif desired, as where a large area is to be controlled. By using twounits and placing them at different depths in the soil it is possible toaccurately control depth of irrigation under a variety of conditions. Itoften happens that the upper surface layer of soil becomes dried outwhile there is still sufiicient moisture at lower levels. At othertimes, as after a light rain, the surface soil may be quite wet and yetat a depth the ground may be too dry. With two such detector unitsconnected in series and buried at different depths these conditions maybe detected and irriga tion supplied as required.

In connecting the detector units I prefer to connect the outerelectrodes of the devices together, as by a length of insulated wire '79(Fig. l). The inner electrodes are connected one to the common line 41and the other to one of the contact points of the detector selectorswitch 36. Thus the inner electrodes are at the voltage potential of thedetector circuit and the outer electrodes, being connected together, areboth at the same potential. The construction of the detectors and themanner of connecting them thus prevents the current taking an undesiredpath through or over the soil and makes possible an accuratedetermination of the moisture of the soil in the given areas.Furthermore, since alternating current is employed, electrolysis iseliminated.

The operation of the system is as follows: The time clock switch is setto operate at any desired hour, at

An insulation covered conductor after a slight delay as previouslyexplained, the delay permitting starter anode current to flow with theresult that current flows through the tube energizing relay 56 andclosing the switch portion 55 thereof. With the closing of the switch,the circuit through the step relay 48 is closed and energization of thisrelay advances the two detector switches to the next switch contactpoint.

The step relay, after advancing the selector switches, opens the breakerswitch 48a which is in series in the plate circuit of the tube. When theplate circuit is opened, relay 56 is deenergized and the step relay isdeenergized.

On the first actuation of the step switches, the movable contact arm 38of switch 36 makes contact with button 37a thereby bringing the moisturedetector units 18a into series in the detector circuit 30. At the sametime, contact arm 43 of step switch 42 makes contact with the button 45aestablishing a circuit through solenoid 16:: which opens valve 15a tobranch irrigation pipe 120. When the area covered by pipe 12a hasreceived suflicient water, the soil, including that within thedetectors, becomes moist enough to lower the impedance of the detectorunits sufiiciently that the resultant flow of current in the detectorcircuit will induce a starting voltage for the tube, current will flowin the plate circuit of the tube closing relay 56 which in turn againenergizes the step relay with the result that the selector switches areadvanced. Of course, if the soil was originally wet, there would be animmediate flow of sufficient current in the detector circuit with theresult that the step relay will immediately kick the selector switchesover to the next contact.

It will be apparent that by adjusting the setting of potentiometer 60,the system may be set to be responsive to any desired degree of moisturein the soil. I may add a condenser 81 in the grid-cathode circuit totake care of variations or surges in the supply circuit and increase theaccuracy. I may also employ a fixed resistor 82 and a variable resistor83, connected in series across the detector circuit, to introduce afurther adjustment in the system.

When the step switches have moved around to their original positions,the system ceases operating until it is disconnected from the source ofcurrent and again connected, as by the normal operation of the timecontrol switch. The reason for this is that the detector circuit is opensince switch 34 remains open after the initial delay in opening of thesame at the start of the operation. Hence transformer 31 is dead and nostarter anode current is supplied to the tube. It may also be noted thatthe movable arm of the power circuit selector switch now rests on thedead contact button so that no current is supplied to any of thevalve-operation solenoids.

In Fig. 4 I show another means of operating the valves which connect themain water supply line with the branch lines. In this form of theinvention I provide a valve 90, the inlet of which communicates with thewater supply pipe 91. A branch irrigation pipe 92 leads from the outletof the valve. A bellows 93 operates valve element 94 which is normallyclosed by the pressure of the water in the supply line.

I provide a pilot valve 95 which is actuated by solenoid 96 connected ina power circuit of the control unit 20. A pressure pipe 97 connects thewater supply line and the pilot valve and a second pipe 98 leads fromthe pilot valve to the bellows of the main valve 96. It will be apparentthat when the solenoid actuates the pilot valve, water under pressure issupplied to the bellows of the main valve opening the valve. When thepilot valve closes upon deenergization of the solenoid, the water underpresure in the bellows is bled to the branch pipe which is atatmospheric pressure by a pipe 99. This pipe is either of relativelysmaller diameter than pipe 98 or has a restriction 100 therein, asshown, for the dual purpose of insuring sufficient pressure to actuatethe main valve and of preventing sudden release of pressure on thebellows such as would permit rapid closing of the main valve withconsequent water hammer.

It will be apparent that the above-described system of Fig. 4 has theadvantage that the pilot valves may be installed wherever desired andsmall diameter copper tubing run to the main valves. This reduces thecost of installation eliminating excessive wiring and large piping.

In Fig. 5 I show another form of the invention Where in a fluid having ahigh coeflicient of expansion contained in bulb 105 and tube 106 is usedfor actuating a bellows or other valve actuator mechanism, indicated at107 and associated with a valve 108 located between supply pipe 109 andbranch irrigation pipe 110. The fluid is heated by electric coil 111which is connected in a power circuit controlled by the control unit 20.Expansion of the fiuid when heated by the coil opens the valve which isnormally closed.

While I have shown and described the control means in connection withand adapted for the control of irrigation systems, it will be apparentthat the electrical control means may be used for the control andoperation of many other types of apparatus and equipment and that it maybe used with other moisture detector units.

I claim:

1. In electrical control apparatus, means for testing the degree ofmoisture in a substance such as soil, comprising a detector circuitincluding moisture-responsive detector means connected in series in thecircuit and adapted to be placed in the substance to be tested, theimpedence of said detector means varying with the degree of moisture insaid substance at said detector means, a source of alternating currentfor energizing said detector circuit, a cold cathode tube, a directcurrent supply for said tube, the cathode and grid of said tube beingcoupled to said detector circuit for furnishing a starter voltage forthe tube, and means for opening the detector circuit, said means beingoperable in response to current fiow in the plate circuit of the tube.

2. Testing means as set forth in claim 1 in which adjustable means areprovided in the grid circuit of the tube for varying the characteristicsof said circuit thereby to adjustably determine the starter voltagerequired to operate the tube.

3. In electrical control apparatus, means for testing the degree ofmoisture in a substance such as soil, comprising a detector circuitincluding moisture-responsive detector means connected in series in thecircuit and adapted to be placed in the substance to be tested, theimpedance of said detector means varying with the degree of moisture insaid substance at said detector means, a source of alternating currentfor energizing said detector circuit, a cold cathode tube, a directcurrent supply for said tube, the cathode and grid of said tube beingcoupled to said detector circuit for furnishing a starter voltage forthe tube, and a relay connected for energization upon flow of current inthe plate circuit of said tube adapted to open said detector circuitwhen the relay is energized.

4. In electrical control apparatus, means for testing the degree ofmoisture in a substance such as soil, com prising a moisture-detectingcircuit including moisture-responsive detector means connected in seriesin the circuit and adapted to be placed in the medium to be tested, theimpedance of said detector means varying with the degree of moisture insaid substance at said detector means, a source of alternating currentfor energizing said detector circuit, a cold cathode tube, a directcurrent supply for said tube, the cathode and grid of said tube beingcoupled to said detector circuit for furnishing a starter voltage forthe tube, and a relay connected for energization upon flow of current inthe plate circuit of said tube adapted to open said detector circuitwhen the relay is energized, said relay also being adapted to open theplate circuit of said tube after opening said detector circuit.

5. In electrical control apparatus, the degree of moisture in asubstance such as soil, comprising a detector circuit includingmoisture-responsive detector means connected in series in the circuitand adapted to be placed in the substance to be tested, the impedance ofsaid detector means varying with the degree of moisture in saidsubstance at said detector means, a source of alternating current forenergizing said detector circuit, adjustable means in said detectorcircuit for varying the characteristics thereof, a cold cathode tube, adirect current supply for said tube, the cathode and grid of said tubebeing coupled to said detector circuit for furnishing a starter voltagefor the tube, and means for opening the detector circuit, said meansbeing operable in response to current flow in the plate circuit of thetube.

means for testing References Cited in the file of this patent UNITEDSTATES PATENTS Number Name Date 1,568,214 Elder Jan. 5, 1926 1,910,021Legg May 23, 1933 1,978,440 Shepard Oct. 30, 1934 2,166,058 Kirk July11, 1939 2,315,733 Pfleger Apr. 6, 1943 2,331,229 Reagan Oct. 5, 19432,364,264 Yeomans Dec. 5, 194-4 2,497,505 Martin Feb. 14, 1950 2,509,027Zimmerman May 23, 1950

